Drugs of abuse are associated with a variety of cognitive deficits including disruption of learning and memory. Animal models are needed to better assess the cognitive risks of use and abuse of psychoactive drugs and the studies completed during the current grant period developed promising procedures to assess drug effects on memory capacity in rats. The proposed work will focus on five key drugs (CDZ, scopolamine, MDMA, DZP and ketamine) of particular interest based on the effects observed in our preliminary work. These proposed studies will 1) use a more refined measure of memory load to test the hypothesis that drug effects in our recently completed studies might have been influenced by attentional factors due the use of multiple distractors. 2) Use a list memory procedure that permits the analysis of both the number of stimuli to remember and the retention interval to test the hypothesis that these drugs have different actions on recognition memory: i.e., NMDA antagonist effects depend on memory load, whereas MDMA, CDZ, and scopolamine effects are delay-dependent. 3) Use an odor list task that includes test trials separating responding based on relative familiarity versus recollection of specific episode sequences to test the hypothesis that NMDA antagonists impair both familiarity and episodic-like memory processes, whereas CDZ, and scopolamine spare familiarity, and MDMA spares both processes. Finally, the proposed research will provide an ideal opportunity for students to develop skills and background in psychopharmacology and neuroscience.